Plant Processes: Gas Exchange and Photosynthesis

1. Plant Processes: Gas Exchange and Photosynthesis

2. What is gas exchange in plants? • When we inhale, we breathe in a mixture of gases we need for survival • When we exhale, we breathe out the waste products • In plants, CO₂ and H₂O are two substances needed for survival • CO₂ enters through the stomata • H₂O is absorbed through roots of the plant and released as water vapor through the stomata

3. Gas Exchange • Light, H₂O and CO₂ all affect the opening and closing of stomata • Stomata are usually open during the day and close at night • When stomata closes, less CO₂ can enter and less H₂O can escape • When plants lose water vapor through stomata, this is called transpiration

4. Photosynthesis • Photosynthesis is the process inwhich plants use light energy to make food • Chlorophyll is a chemical in plants that helps to capture this light energy • Other than light, plants also need H₂O and CO₂ • These molecules combine to form an organic compound, a carbohydrate (sugar) called glucose

5. Process of Photosynthesis 6CO₂ + 6H₂O + light energy  C₆H₁₂O₆ + 6O₂ Carbon dioxide + water + light (and chlorophyll) produces glucose and oxygen • A plant needs 6 molecules of carbon dioxide (CO₂) and 6 molecules of water (H₂O) to make one molecule of glucose (C₆H₁₂O₆) • The chemical bonds in glucose contain the energy the plant needs for growth and survival and is the main source of food for plants • Oxygen is produced as a waste product during photosynthesis and released through plant stomata